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排序方式: 共有194条查询结果,搜索用时 15 毫秒
1.
Gilberto Abate Luciana B.O. dos Santos Sandro M. Colombo Jorge C. Masini 《Applied Clay Science》2006,32(3-4):261-270
Clay minerals are low cost materials that can be structurally modified and exploited for removal of natural organic matter from freshwaters. The present study shows that vermiculites modified by ion exchange with hexadecyltrimethylammonium or intercalation with poly(hydroxy iron) cations are potential adsorbents for removal of fulvic acid, whereas the adsorption on the raw clay mineral is negligible. The efficiency of the modified vermiculite was evaluated by measuring adsorption isotherms by the batch technique using initial fulvic acid concentrations between 2.5 and 50.0 mg L− 1, with one hour of contact time. At least 94% of the fulvic acid initially present in a 20 mg L− 1 solution was sorbed onto either the intercalated poly(hydroxy iron) cations or the organically modified vermiculite. Up to an initial concentration of 5.0 mg L− 1 the adsorption is irreversible, and no quantifiable fulvic acid was measured in the desorption experiments. For initial fulvic acid concentrations between 10.0 and 50.0 mg L− 1, desorption was between 2.3% and 4.9% for Fe(III) intercalated vermiculite, and between 1.4% and 9.2% for the organoclay. The adsorption percentages on intercalated poly(hydroxy iron) cations increased upon lowering pH and increasing the ionic strength, indicating the occurrence of strong binding mechanisms such as ligand exchange. Adsorption percentage of fulvic acid onto the organoclay also increased with lowering of pH, but in this case the adsorption percentages showed a small decrease at high ionic strength, suggesting that electrostatic attraction plays an important role in the adsorption process. 相似文献
2.
Layers of naturally occurring clay minerals are rearranged to prepare highly sensitive multiresponsive clay–clay bilayer membrane (CCBM). The CCBM introduced here responds to the minuscule changes in the surrounding environments including temperature, humidity, and presence of solvent vapors by morphing in specific manners. Strips cut from CCBM exhibit up to 588 N kg?1 force output when exposed to temperature fluctuations. Inheriting the natural stability of clay minerals, CCBM demonstrates extreme robustness, heating up to 500 °C, cooling with liquid N2 and exposure to corrosive chemical vapors did not deteriorate its bending performance. Mechanistic studies suggest that shape transformations of CCBM are driven by the unequal response of its components to external stimuli. 相似文献
3.
In this communication, new composite desiccant materials having 37% concentration of CaCl2 have been compared for water production from atmospheric air. The vermiculite–saw wood, jute and burnt-clay have been used as host materials and CaCl2 as a hygroscopic salt. All the desiccant materials have been tested with the solar glass desiccant box type system (SGDBS) with a collector area of 0.36?m2. Design parameters for water production are: height of the glass from the desiccant bed to be 0.22?m, an inclination angle of 30°, the effective thickness of the glass as 3?mm and the number of glazing is single. It has been found that on the experimental day, the maximum amount of fresh water generated by the vermiculite–saw wood/CaCl2 is 130?ml/kg/day. 相似文献
4.
从国内外专利看我国蛭石开发利用与世界的差距 总被引:4,自引:0,他引:4
介绍了蛭石的性质及国内外蛭石利用专利情况,分析了在应用领域、产品品种、加工处理方法等方面我国与国外的差距。 相似文献
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通过实验探讨了Na型蛭石在不同的Pb2 溶液浓度和不同的温度下的2Na =Pb2 离子交换动力学关系,实验结果表明:蛭石中2Na =Pb2 离子交换很快,0.5min以内交换吸附率已达70%~80%以上,达到交换平衡的时间与溶液的起始浓度和交换时的温度有关,原液浓度越大达到平衡所需要的时间越长,温度越高交换越快;蛭石中2Na =Pb2 离子交换过程受粒内扩散控制;动力学方程符合克-金-布扩散(粒内扩散)方程;计算出了蛭石中2Na =Pb2 离子交换过程的表观活化能E'a的平均值为25.21kJ/mol;推导出了蛭石中2Na =Pb2 离子交换过程的动力学方程为:1-2/3α-(1-α)2/3=k0r-20exp-(25.21/R)·1/Tt 相似文献
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受全球能源形势与环境问题影响,新型膜分离技术尤其是二维层状膜在分离领域展现出广阔的应用前景。然而,目前使用的二维纳米材料化学环境相对复杂,且膜制备成本高昂,限制了其工业化推广。天然蛭石廉价易得,剥离简单,表面只含有硅羟基且其含量易于调控,可精确调控所制备层状膜层间亲疏水性,实现有机溶剂的高效渗透和极性与非极性溶剂的高效分离。研究发现:蛭石层状膜展现出优异的极性溶剂分子传递能力,而非极性溶剂则相对较低,其中乙腈分子渗透性高达1650L/(m2·h·bar)(1bar=0.1MPa),甲苯分子渗透性仅为37.8L/(m2·h·bar),乙腈与甲苯的分离因子高达43.6,展现出优异的分子分离性能。本文所制备蛭石层状膜具有1.36nm的规则平直层间传递通道,对分子动力学直径大于层间距的结晶紫(1.5nm)、亮蓝(1.6nm)、酸性黄14(1.9nm)等染料分子的截留率均大于90%,截留性能优良。同时,蛭石层状膜具有良好的压力循环稳定性及抗污染能力, 展现出巨大的分离应用潜力。 相似文献
10.
Jinglin Zhang Huidi Liu Zhimin Wu Weibing Xiang Shuiping Wen Xiang Cai 《塑料、橡胶和复合材料》2017,46(8):333-340
To improve the dispersion of organically modified vermiculite (OVMT) in polymethylmethacrylate (PMMA), the method of ultrasonic in situ polymerization was introduced, and a series of OVMT/PMMA nanocomposites were successfully prepared. The structure, morphology, and mechanical and thermal properties of as-prepared sample had been investigated. Results showed that the assistance of ultrasonic irradiation could be beneficial for the good homogeneous dispersion and strong interfacial interaction of OVMT in PMMA. Consequently, the obtained nanocomposites showed better mechanical and thermal properties than those prepared without the assistance of ultrasonic irradiation. When the OVMT content was 3 wt.%, the nanocomposite prepared by ultrasonic in situ polymerization exhibited the Young's modulus, tensile strength, elongation at break and degradation temperatures for 5% and 50% weight loss of 1177 MPa, 65 MPa, 14%, 219.82ºC and 373.91ºC, respectively. These results suggested the great potential application of ultrasonic in situ polymerization for the synthesis of polymer/clay nanocomposite. 相似文献